An eccentric screw pump typically has at least one stator and one rotor rotatable in the stator. A suction housing is provided at one end of the stator and a connector at the axially opposite other end. The rotor is attached inside the suction housing to a coupling rod or drive shaft via a universal joint having an input-side first part and a rotor-side second part swivelable relative to the first joint part. The rotor is detachably connected to the second joint part of the joint.
The stator is normally made of an elastic material and is enclosed by a rigid stator casing, made for example of metal. According to the invention, the elastic material is an elastomer, for example a synthetic rubber or rubber mixture. The stator casing and elastically deformable stator are preferably separate parts.
During operation, the elastically deformable stator os subject to wear so that at regular intervals maintenance must be performed or the stator must be switched out. In order to exchange the stator that is installed between the suction housing and the connector element, in practice it has been necessary to uninstall the suction housing and/or connecting housing. Since an eccentric screw pump is frequently integrated into a system that has a plurality of other parts, as a rule such disassembly is a complex process. The same is true for exchanging the rotor.
In order to simplify replacement of the elastomer stator, it has already been suggested that the stator of an eccentric screw pump be longitudinally split so it has at least two stator parts. In this manner the elastically deformable stator may be exchanged without having to take the pump apart (see US 2010/0196182).
Alternatively, it was suggested that a spacer ring that can be removed for disassembling the stator be provided between the stator and connecting housing. This spacer ring can be uninstalled and removed with the connecting housing installed and with the stator installed so that after the spacer ring is uninstalled it is simple to change the stator, specifically without having to disassemble the suction housing and the connecting housing (see DE 10 2008 021 919). Here as well, the stator can be changed without uninstalling the rotor.
Finally, it has already been alternatively suggested that the suction housing be equipped with a removable housing segment in order thus to be able, after taking off the removable housing segment, to release the connection between the rotor and the coupling rod so that the stator can be removed with the rotor inside. In order to further simplify this option, it was further suggested that the rotor be detachably connected to the second joint part of the universal joint. Such an eccentric screw pump of this type is also known from DE 10 2008 021 919. A separable connection is provided between the second joint part and the rotor such that the universal joint does not itself have to be taken apart. The second joint part is consequently no longer an integral part of a conventional rotor, but rather is an independent part that is detachably connected to the actual rotor or section of a rotor. This system makes changing the stator much simpler.
In DE 199 43 107 an eccentric screw pump is described for emptying a silo where the pump is used in combination with a screw conveyor. For maintenance purposes, for example for rotor exchange and stator exchange, the eccentric screw pump must be separated from the adjacent screw conveyor. A closure element for sealing off the pump from the screw conveyor is described for this. Since it is no longer possible to separate the universal joint itself, it is suggested that the rotor be connected to the coupling shaft via an intermediate shaft, the intermediate shaft having a polygonal end facing the coupling shaft and the coupling shaft being provided on its end facing the intermediate shaft with a complementary polygonal socket for coupling to the shaft.
A similar embodiment is known from DE 20 2007 013 820 that describes an eccentric screw pump for viscous media in which additional conveyor elements or treatment elements are also provided.